Mesenchymal stem cells are pluripotent stem cells derived from various adult cells such as bond mallow cells, umbilical cord blood cells, placental cells (placental tissue cells) or adipose cells (or adipose tissue cells). For example, mesenchymal stem cells from bone marrow have pluripotency to differentiate into adipose tissue, bone/cartilage tissue and muscular tissue, and thus various studies on the development of cell therapeutic agents using mesenchymal stem cells have been conducted.
In recent years, as cell therapy technology utilizing mesenchymal stem cells has received attention, the development of the technology of activating mesenchymal stem cells from the human body so as to be suitable for therapeutic purposes has been required. Particularly, aged persons make up a significant portion of cell therapy patients, and mesenchymal stem cells collected from the tissue of an aged person have low therapeutic efficiency due to their low ability to proliferate and differentiate. In addition, technology of activating mesenchymal stem cells from an aged person to have characteristics similar to those of mesenchymal stem cells from young people has been required.
It is known that mesenchymal stem cells divide very slowly due to a senescence mechanism not associated with telomere shortening when being cultured in vitro, similar to other primary cultured human cells (Shibata, K. R. et al., Stem cells, 25; 2371-2382, 2007). This senescence mechanism has not yet been clearly found, but is known to occur mainly because environmental stress accumulates during long-term in vitro culture so that the Cdk inhibitory protein p16(INK4a) is expressed and accumulated to inhibit the activity of the Cdk protein that is involved in the growth of cells. It was found that, when the expression of the tumor gene Bmi-1 in mesenchymal stem cells was induced to inhibit the expression of p16, the senescence of the cells was inhibited (Zhang, X. et al. Biochemical and biophysical research communications 351; 853-859, 2006). In addition, it was reported that, when mesenchymal stem cells were treated with FGF-2 during culture to inhibit the mRNA expression of p21(Cip1), p53 and p16(INK4a), the arrest of growth of the mesenchymal stem cells in the G1 phase was inhibited (Ito, T. et al., Biochemical and biophysical research communications, 359; 108-114 2007). Moreover, Korean Patent Laid-Open Publication No. 10-2009-0108141 discloses a method of inhibiting the senescence of mesenchymal stem cells by transforming the mesenchymal stem cells with a gene encoding the Wip1 protein.
However, a method for rejuvenating aged mesenchymal stem cells collected from the tissue of an aged person has not yet been reported.
Accordingly, the present invention have found that, when mesenchymal stem cells collected from the adipose tissue isolated from an aged patient are cultured in a medium containing an antioxidant and a growth factor, mesenchymal stem cells having activity similar to that of the mesenchymal stem cells of young people can be produced, thereby completing the present invention.